// DatasetSelectionCatalog.h 

#ifndef dset__DatasetSelectionCatalog_H
#define dset__DatasetSelectionCatalog_H

// David Adams
// November 2004
//
// A dataset selection catalog associates named attributes with dataset
// names. Each entry in the catalog has a unique name. The attributes
// include those used to record a dataset ID.
//
// This class is built on a generic selection catalog.

#include <string>
#include <iosfwd>
#include "dataset_sql/SqlQuery.h"
#include "dataset_id/DatasetId.h"
#include "dataset_id/DatasetIdList.h"
#include "dataset_catalog/GenericSelectionCatalog.h"

namespace dset {

class DatasetSelectionCatalog {

public: // typedefs

  typedef std::string Connection;
  typedef GenericSelectionCatalog::Name Name;
  typedef GenericSelectionCatalog::NameList NameList;
  typedef GenericSelectionCatalog::size_type size_type;
  typedef GenericSelectionCatalog::Attributes Attributes;
  typedef DatasetIdList IdList;
  
private: // Data
  
  GenericSelectionCatalog* m_pcat;

private:

  // No copying allowed.
  DatasetSelectionCatalog(const DatasetSelectionCatalog&);

  // No assignment allowed.
  DatasetSelectionCatalog& operator=(const DatasetSelectionCatalog&);

public:  // static methods

  // Return the default concrete instance of this class.
  // First pass, use set_default_instance or 
  // define an invalid catalog if this fails.
  static DatasetSelectionCatalog& default_instance();

  // Set the default instance of this class.
  // The class takes ownership of the argument and deletes it the
  // next time the default instance is changed.
  // Returns 0 for success.
  static int set_default_instance(DatasetSelectionCatalog* pdsc);

  // Set the default instance of this class.
  // The connection is used with the connection resolver to construct
  // a and new default catalog.
  // Returns 0 for success.
  static int set_default_instance(Connection conn ="");

  // Assign an empty DSC as the default by
  // 1. creating an empty SQLRESULT DSC dsc.dat,
  // 2. appending a clause to resolver.dat and
  // 3. setting the latter as the connection configuration file.
  // This should only be used for testing.
  // The connection resolver is shared by all catalogs.
  // Returns 0 for success.
  static int create_default_instance();

public:  // methods

  // Default constructor.
  // Produces an invalid catalog.
  DatasetSelectionCatalog();

  // Constructor from a generic selection catalog.
  // Argument must have catalog type DatasetSelectionCatalog.
  // This class takes ownership (deletes) the input catalog.
  explicit DatasetSelectionCatalog(GenericSelectionCatalog* pcat);

  // Constructor from a catalog connection.
  explicit DatasetSelectionCatalog(Connection conn);

  // Destructor.
  virtual ~DatasetSelectionCatalog();

public:  // const methods

  // Is this a valid catalog?
  virtual bool is_valid() const;

  // Catalog type: DatasetSelectionCatalog.
  virtual Name catalog_type() const;

  // Return the ID encoding.
  virtual Name id_encoding() const;

  // Return the attribute names.
  virtual NameList schema() const;

  // Does a dataset name appear in the catalog?
  virtual bool has_name(Name name) const;

  // Retrieve the attributes associated with a name.
  virtual Attributes attributes(Name name) const;

  // Return the ID associated with a dataset name.
  virtual DatasetId id(Name name) const;

  // Return the number of entries in the catalog.
  virtual size_type size() const;

  // Return the namess for the first maxent datasets that match a query.
  virtual NameList query(SqlQuery qry, size_type maxent =20) const;

  // Retrieve the number of entries that match a query.
  virtual size_type query_count(SqlQuery qry) const;

  // Return a web page.
  // See GenericSelectionCatalog.
  Text web_page(std::string baseurl, std::string entry,
                std::string uidurl) const;

public:  // non-const methods

  // Insert a new entry with attributes.
  // Error if name is already present or catalog cannot be updated.
  // Value for name in attribute list is overwritten.
  // Error if name is already present.
  // Returns 0 for success.
  virtual int insert(Name name, const Attributes& att);

  // Update the attributes for an existing entry.
  // Error if name is not present or catalog cannot be updated.
  // Attributes may be used to rename the dataset.
  // Error if this attribute name is already present.
  // Returns 0 for success.
  virtual int update(Name name, const Attributes& att);

  // Remove an entry.
  // Error if name is not present or entry cannot be removed.
  // Returns 0 for success.
  virtual int remove(Name name);

};

}  // end dset namespace

// Output stream.
std::ostream&
operator<<(std::ostream& lhs, const dset::DatasetSelectionCatalog& rhs);

#endif